The theory, feasibility and accuracy of an ultrasonic method of estimating fetal weight

We present the theory, method, feasibility and accuracy of estimating fetal weight by measuring the fetal volume using compound ultrasonic scanning. The two parameters had a very high coefficient of correlation (0-9794), and the standard error in one series of 20 patients was only +/- 106 g. The correlation coefficient achieved by one of us who was new to ultrasound techniques was 0-82, which compared favourably with correlations between fetal weight and biparietal diameter measurements (r = 0-26). A discussion as to the correction factors required to allow for the unknown value of the velocity of ultrasound in fetal tissues, the clinical use of this method, and the possible means by which the accuracy of estimating fetal weight may be further improved is included.